From b1d2aba0f30eadccdfe93f735c35a557c411a2df Mon Sep 17 00:00:00 2001
From: Robin Ward <robin.ward@gmail.com>
Date: Mon, 26 May 2014 13:26:28 -0400
Subject: [PATCH] Clean up notifications if a user can't see a topic

---
 app/controllers/topics_controller.rb | 8 ++++++++
 app/models/notification.rb           | 6 ++++++
 2 files changed, 14 insertions(+)

diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index 45828cca829..71c6a46bec8 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -61,6 +61,14 @@ class TopicsController < ApplicationController
     perform_show_response
 
     canonical_url absolute_without_cdn(@topic_view.canonical_path)
+  rescue Discourse::InvalidAccess => ex
+
+    if current_user
+      # If the user can't see the topic, clean up notifications for it.
+      Notification.remove_for(current_user.id, params[:topic_id])
+    end
+
+    raise ex
   end
 
   def wordpress
diff --git a/app/models/notification.rb b/app/models/notification.rb
index 4713d9c863c..55ebdcae66b 100644
--- a/app/models/notification.rb
+++ b/app/models/notification.rb
@@ -65,6 +65,12 @@ class Notification < ActiveRecord::Base
     result
   end
 
+  # Clean up any notifications the user can no longer see. For example, if a topic was previously
+  # public then turns private.
+  def self.remove_for(user_id, topic_id)
+    Notification.where(user_id: user_id, topic_id: topic_id).delete_all
+  end
+
   # Be wary of calling this frequently. O(n) JSON parsing can suck.
   def data_hash
     @data_hash ||= begin